A low dielectric constant controlled impedance coaxial cable is currently constructed with insulated signal and integrated drain conductors formed into a closely spaced flat cable having closely-spaced parallel conductors, conductive shielding attached to both sides of the cable, then an outer protective coating or jacket applied.
This construction allows a high fidelity controlled impedance signal cable to be formed which can be terminated to insulation displacement connectors. A low dielectric constant porous polytetrafluoroethylene or a foamed polymer insulation allows these electrical characteristics.
However, recent developments in insulation displacement connectors which provide for efficient high density use of tightly spaced printed circuit board (PCB) footprints allow use of as little as 50% of the PCB surface space with the same signal to pin ratio. This is accomplished by placing two 0.050 inch pitch flat cables into a single connector and maintaining the 0.050 inch spacing through the connector into the PCB. Presently available flat cables of 0.050 inch pitch can be accepted into a connector, but the connector converts the PCB pin spacing to 0.100 inch. If the cable is made with a pitch of 0.025 inch and used with a similar 0.025 inch cable, the PCB pin spacing is 0.050 inch, but that high pin density allows use of signal conductors of only 30 AWG maximum conductor size.
It would be desirable to have a single high-density cable having shielded conductors of larger than the presently usable size along with controlled impedance and matable with a high-density insulation displacement connector. The invention provides a cable which solves the problem of good properties with very close spacings.